A new paper appeared in Climatic Change this week by Visser et al. which looks at disasters and climate change (open access here). Like other studies and the IPCC assessment, Visser et al. find no trends in normalized disaster loses, looking at several metrics of economic and human losses.

They conclude:

The absence of trends in normalized disaster burden indicators appears to be largely consistent with the absence of trends in extreme weather events. This conclusion is more qualitative for the number of people killed. As a consequence, vulnerability is also largely stable over the period of analysis.

The top line conclusion here is not surprising, though it is interesting because it uses independent methods on largely independent data. It is consistent with previous data and analyses (e.g., Bouwer 2011, Neumayer and Bartel 2011, Mohleji and Pielke 2014) as well as with the conclusions of the recent IPCC assessments (SREX and AR5).

What is perhaps most interesting about this new paper is their discussion of vulnerability. Some have argued that our methodological inability to fully account for possible changes in vulnerability to losses over time may mask a climate change signal in the data. (It's gotta be there somewhere!) This line of argument has always been suspect, because there are not relevant trends in phenomena such as floods and hurricanes which would lead to an expectation of increasing normalized losses.

Visser et al. take this issue on and offer several explanations as to why vulnerability does not mask any hidden signals:

Firstly, global disaster management initiatives have only recently been put in place. The Hyogo Framework for Action (HFA) was adopted by 168 Member States of the United Nations in 2005 to take action to reduce vulnerabilities and risks to disasters (UNISDR, 2011). Although these highly important efforts will certainly pay off in the near future, it is unclear whether they are reflected in the sample period chosen for this study. Similar conclusions are drawn in IPCC (2014). . .

Secondly, it is unclear to what extent adaptation measures work in practice. Heffernan (2012) argues that many countries, and even the richest, are ill-prepared for weather extremes. As an example, he names Hurricane Sandy, which wreaked a loss of 50 billion USD along the northeast coast of the US in 2012. As for early warning systems, Heffernan states that not all systems are functioning well. For example, in 2000, Mozambique was hit by a flood worse than any in its history, and the event was not at all anticipated. Warnings of above-average rainfall came too late and failed to convey the magnitude of the coming flood.

Thirdly, a positive trend in vulnerability may be offset by the increasing number of people moving from rural to urban environments, often situated in at-risk areas (UN 2012). Since many large cities lie along coastlines, these movements will make people more vulnerable to land-falling hurricanes (Pielke et al. 2008), coastal flooding and heatwaves (due the urban heat island effect). With regard to economic losses, Hallegatte (2011) argues that these migration movements may have caused disaster losses to grow faster than wealth.

Fourthly, it is unclear how political tensions and violent conflicts have evolved over large regional scales since 1980. On the one hand, Theisen et al. (2013) show that the number of armed conflicts and the number of battle deaths have decreased slightly at the global scale since 1980. On the other hand, these methods are rather crude as far as covering all aspects of political tensions are concerned (Leaning and Guha-Sapir et al. 2013).

We conclude that quantitative information on time-varying vulnerability patterns is lacking. More qualitatively, we judge that a stable vulnerability V t, as derived in this study, is not in contrast with estimates in the literature.

In short, those who claim that a signal of human caused-climate change is somehow hidden in the disaster loss record are engaging in a bit of unjustified wishful thinking. The data and evidence says otherwise.

The bottom line? Once again, we see further reinforcement for the conclusion that there is no detectable evidence of a role for human-caused climate change in increasing disaster losses. In plain English: Disaster losses have been increasing, but it is not due to climate change.

Roger Pielke Jr. is a professor of environmental studies at the Center for Science and Technology Policy Research at the University of Colorado at Boulder. He also holds appointments as a Research Fellow, Risk Frontiers, Macquarie University; Visiting Senior Fellow, Mackinder Programme, London School of Economics; and Senior Visiting Fellow at the Consortium for Science, Policy and Outcomes ...

The consequences of excess CO2 will be felt very little at first. Past disasters are just one indicator (that I haven't even really thought about). The real indicators are the usual scientific measurements.

This is a big planet, however, from a human timescale, it takes a long time for nature to melt the icecaps, which causes warmer waters, a lessening of the polar driven current, causing ocean anoxia, causing the possibility of the worst (nevermind mere sea level rise). You may want to take that chance... I don't. There is also the chance that the changes in chemistry (more carbonic acid) will cause problems concerning the global food chain. Again, I don't want to take that chance.

Last year alone, we emitted 1/14th of the entire historical total of numan caused excess CO2 (~35 gigatons)! It is unfortunate that there is no overall coherent (abundant and reliable) strategy considered, let alone, set in sights, to replace our global accelerating combustion of FF's (besides the mere little fill ins from renewables and efficiency).

President Kennedy's science advisor, Alvin Weinberg was already keen LONG before Al Gore, and unlike Al, Alvin had a solution!

Roger, in this post and others you seem intent on arguing, either directly or by inference, that climate change is not in and of itself dangerous to people and property. Correct me if that's a mischaracterization.

The evidence that you present, including this paper, doesn't support that conclusion. At best, it shows that a clear signal implicating climate change in increased disaster losses and loss of life has not been found. There's a significant logical leap taken between that and

Disaster losses have been increasing, but it is not due to climate change.

This is classic modus tollens of criminal law or propositional logic:

A implies B. B is false, therefore A is false.

or colloquially: absence of evidence is not evidence of absence. To their credit, the authors of the paper specifically acknowledge such a conclusion is unwarranted:

A positive trend in climatological events can not therefore be ruled out, which applies to those regions where climatological events play a dominant role.

They're left to searching for an answer of why disaster losses shouldn't be less than they are right now, given improvements in adaptive measures. Though they acknowledge

This question is difficult to answer since quantitative information on vulnerability and vulnerability changes is sparse.

they do offer some hypotheses, all of which are unconvincing:

First, global disaster management initiatives have only recently been put in place.

Has global communication not improved during the period under study? Have weather forecasting and medical technology not made similar strides?

Secondly, it is unclear to what extent adaptation measures work in practice. Heffernan (2012) argues that many countries, and even the richest, are ill-prepared for weather extremes.

This, obviously, doesn't diminish the likelihood that preparation has improved during the period under study.

Thirdly, a positive trend in vulnerability may be offset by the increasing number of people moving from rural to urban environments, often situated in at-risk areas.

Assuming that a positive trend means less vulnerability, this is probably true. Nonetheless, adaptive strategies which encourage people to remain in rural areas when jobs have moved elsewhere will likely be unproductive, and this trend must be accepted as a given - shifting responsibility from adaptation to mitigation.

Another question is this: does the study account for money being spend on disaster prevention?

For example, my understanding is that the U.S. Forest Service now has to spend a much larger amount of money fighting forest fires. Okay, so there are no more homes being destroyed than before, but much more money is being spent saving homes from fires.

In New York, Consolidated Edison is spending billions adapting the infrastructure to climate change. I assume that this sort of prevention is not accounted for.

Also, with increasing drought, more water is being pumped out of aquafiers, which are being depleted. The cost is deferred to the future.

"For example, my understanding is that the U.S. Forest Service now has to spend a much larger amount of money fighting forest fires. Okay, so there are no more homes being destroyed than before, but much more money is being spent saving homes from fires."

If the US Forest Service is indeed spending more fighting forest fires, it's because there are more homes being built in or near forested areas. But don't let a fact interfere with conjecture and modelling.

"Suppression costs are increasing due to several reasons that can be categorized according to socioenvironmental, institutional, and operational factors. The most popularly cited reasons for rising suppression costs are the socioenviromental factors of excess fuels accumulations caused in part from past fire suppression, expansion of housing development in the wildland/urban interface (WUI), and climate change from global warming fueled primarily by human-caused fossil fuel burning. Of these three, climate change is the dominant factor affecting increased wildfire activity and fire size due to its effect on weather and vegetation and length of wildfire season. "

But if disaster losses have not, in the recent past, increased due to climate change, does that mean they will not increase in the future?

The impact of climate change is not necessarily linear. Most infrastructure was built with some margin of error to cope with the randomness of weather events. So the damage will be non-linear when the margin is exceeded. There will likely be a jump condition. Eigtht inches of sea level rise, the levee holds, but with twenty four inches, the levee fails -- suddenly, in a storm, not as a gradual process.

And of course those who wish to do nothing about climate change sieze on reports like this and prefer to extrapolate them into the future.